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Thursday, 29 November 2012

Caution! Nature's Genetic Engineers at Work

There have been many critics of the use of genetic engineering techniques to transfer genetic material from on species to another as the process is viewed as potentially dangerous, changing some modified organisms in ways that were impossible by natural processes and thus generating organisms that may be harmful to the environment in some way.

However it is becoming increasingly clear that although natural mechanisms that pass genetic material from one generation to the next i.e. sexual or asexual reproduction remain by far the most common, there are natural mechanisms that pass genetic material - in some cases containing many genes - to and from species between which sexual reproduction is not thought possible.

We have been aware of horizontal genetic transmission for many years but it had been assumed that it was rare and limited in cope - we have noticed it happening in bacteria and viruses. A recent research paper suggests that that view should be changed. Antonis Rokas, assistant professor of biological sciences at Vanderbilt and research associate Jason Slot found that a large piece of DNA containing 23 genes had transferred from Aspergillus nidulans to Podospora anserina or vice versa at some point in evolutionary history millions of years ago.

Finding evidence for horizontal transfer of quite large gene clusters between eucaryotic organisms that are far more complex than bacteria & viruses is quite a surprise and suggests that this process is far more widespread than we thought even a few years ago, and changes the way we should now think of what defines a species and how genes can potentially be transferred between any living organism. This paper suggests that fungi can pass between them 'cassettes' of DNA containing many genes that can work together to allow the fungus to exploit a new advantage - in this case produce a toxin that would give it a competitive advantage when growing under certain conditions in the wild. In some ways this is similar to one workman lending his specialised tool to another so that he can carry out a task more efficiently.

This may well account for some of the versatility of ability of fungi to live on a huge range of foods and substrates, producing a massive range of metabolites.

How such substantial gene transfer happened remains something of a mystery as known mechanisms tend to provide ways to transfer much smaller pieces of DNA compared with this finding.

Perhaps then nature has been carrying out its own genetic engineering for millions of years, predating human efforts by a very long time!